Summary: Alzheimer's disease (AD) is a progressive neurological disorder that is marked by the presence of amyloid- plaques, neurofibrillary tangles and cognitive deficits. The economic impact of this disease is staggering and is expected to exceed $1 trillion dollars by the year 2050. Early diagnosis and treatment can substantially reduce the economic burden related to AD. Specifically, being able to assess early pathological changes in specific brain areas could be beneficial for diagnosis and treatment. The locus coeruleus (LC), which provides the majority of the noradrenergic innervation to areas such as thalamus, cortex and hippocampus, undergoes extensive neurodegenerative changes. These changes that occur in the LC have been described as the earliest pathologies observed in AD and, critically, appear at least a decade ahead of the neurocognitive deficits. LC noradrenergic neurons are involved in regulating key neurobehavioral functions such as cognition, arousal and wakefulness. However, assessing changes in LC over the course of AD in patients remains a major challenge. The main objective of the proposed research in phase 1 is to develop an organic nanoparticle-based MRI imaging agent to non-invasively monitor noradrenergic neurons in the LC using a preclinical model of AD. Our preliminary studies provide evidence that these nanoparticles are taken by noradrenergic neurons in the brainstem and facilitate the imaging process. Our specific aims are to 1. To assess the ability of the nanoparticles to image the LC using MRI, and correlate with changes in norepinephrine levels. 2. To assess whether these particles can be used to measure degenerative changes as the disease progresses. Translating this to larger animal models and conducting preclinical testing will be next step following this STTR.